Wikipedia:Reference desk/Archives/Science/2010 January 11

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

January 11

Pace of CO₂ Capture

The OP apparently knows more about this subject than we do, so this section serves no purpose. --Tango (talk) 16:53, 11 January 2010 (UTC)

This begins a hidden part. Go to bottom for the part that is currently asking for a response.Julzes (talk) 02:23, 12 January 2010 (UTC)

This is a set of questions related to one I asked recently. It's about the pace at which a single device could remove Carbon Dioxide from the atmosphere.

Assume a device with an orifice a kilometer in diameter is placed at altitude one kilometer and pulls air through it at a rate of 100 kilometers per hour, transforming all of the Carbon Dioxide and some of the water vapor in it into a precipitable chemical (Just assume this part for now) before returning it. How long would it take before CO₂ levels would be at pre-industrial levels? Assume the atmosphere mixes perfectly.

What would be the power expended in the fan of such a device?

What would be the ideal chemical for precipitation, what would be the process chemically, and what would be the power expended in doing this at the same pace as the capture process?

Assuming that a fraction f of the sunlight is used from it, what size array of mirrors parallel to Earth in orbit would produce the power of the processes above?

I don't know if anyone can get the middle part involving the chemical process, but I'd like to see if the other parts have reasonable answers. —Preceding unsigned comment added by Julzes (talk • contribs) 18:36, January 10, 2010

According to Carbon dioxide#In the Earth's atmosphere, industrial activity has increased the amount of CO2 by 35%. That means you would need to process 26% of the atmosphere. The total mass of the atmosphere is about 5x10¹⁸ kg, so we need to process 1.30x10¹⁸ kg of air. At sea level air pressure, that corresponds to a volume of roughly 10¹⁸ m³. Your device processes 314 cubic kilometers an hour. That means it would take about 300 billion years to do the job (and that's ignoring further CO2 emissions). I think we need another plan! --Tango (talk) 22:51, 10 January 2010 (UTC)

Tango, I got about 2000 years. I'm not sure where you lost the thread but 300 billion is not reasonable. Dragons flight (talk) 22:59, 10 January 2010 (UTC)

Using Tango's volume for air, I got 1453 years [1]. Ariel. (talk) 23:20, 10 January 2010 (UTC)

Assuming T's numbers, 10^18/300.10^9/24/365 ~ 380 years for me William M. Connolley (talk) 23:21, 10 January 2010 (UTC)

Tango: He said diameter, not radius. So it's 78.5 cubic kilometers an hour, not 314. Ariel. (talk) 23:31, 10 January 2010 (UTC)

380 years doesn't work. (Even allowing for diameter/radius confusion.) That's the time it would take assuming that the "treated air" was somehow kept separate from the untreated air. Once the air you processed in year one mixes back into the atmosphere, the efficiency of the carbon removal in year two will be diminished. APL (talk) 00:27, 11 January 2010 (UTC)

True, but since we're only trying to remove 26% of the CO2 the diminishing returns won't be too significant. You might need to add about 10% on to the total time, but not much more. --Tango (talk) 01:11, 11 January 2010 (UTC)

Ok, so I don't know what a kilometre is... Nor a diameter... But otherwise, I did well, didn't I? ;) So, it ought to be 75 years (divide my initial answer by a billion to correct for the kilometre issue and by 4 to correct for the diameter issue). We now have 4 different people getting 4 completely different answers... Perhaps it is time to close the Ref Desk... --Tango (talk) 23:55, 10 January 2010 (UTC)

I still don't know what a diameter is. It's multiply by 4, not divide by 4, so I get 1500 years (with more precise calculations, I agree with Ariel). --Tango (talk) 00:00, 11 January 2010 (UTC)

About 25 gigawatts to run such a fan, assuming it draws from air at rest (which would be stupid, but gives you an idea). That's the power equivalent to 18 km² of sunlight in space at normal incidence (or probably an area 5-10 times larger with realistic efficiencies for solar based power collection). Dragons flight (talk) 23:14, 10 January 2010 (UTC)

As for as the chemical part of your question: There is no chemical that can do the job, not without a massive input of energy. And if you had such energy available, just use it and let plants take care of the CO2 in the air.

I know these questions are interesting, but trying to find a way remove CO2 from the air is not necessary. What's necessary is finding a source of energy that does not involve hydrocarbons. If we did that, plants would take care of the CO2 in the air for us. And of course we have such an energy source, but it's slightly more expensive than hydrocarbons. Ariel. (talk) 23:42, 10 January 2010 (UTC)

What is that slightly more expensive energy source?Cuddlyable3 (talk) 23:51, 10 January 2010 (UTC)

There are lots of them. Wind, tidal, solar, nuclear, hydro... --Tango (talk) 23:57, 10 January 2010 (UTC)

Okay, as a follow up, set the question at pre-WW2 levels, double that from 'diameter' to 'radius', assume re-forestation accompanies it so that as much land as is available is (small) forest in 40 years (This may be the hardest part to calculate), and refute the non-sensical claims on chemistry and what is needed by Ariel. Then what's the time period? And, by the way, the solar array is envisioned as being transported in thin pieces stacked like potato chips in a can and then robotically spread out and used for a massive solar furnace. Is the idea for a beam directed at effectively one small area (top of mount Chimborazo) manageable with what is known of high-temperature optics? Directing optics are needed using at least three satellites.Julzes (talk) 00:48, 11 January 2010 (UTC)

Make it a mile in diameter, half a mile altitude (Don't ignore the altitude, but do assume the outflow is at significant distance), and 80 miles per hour. This was the original set of conditions that I thought up. It is quite clear that pre-WW2 and re-forestation must be added to get close to a reasonable time. The conversion to a hydrocarbon of density sufficiently greater than air--is that endo- or exoergic?Julzes (talk) 01:03, 11 January 2010 (UTC)

You may also be interested in artificial trees. ~AH1^(TCU) 01:13, 11 January 2010 (UTC)

I'll take a look at that. Thanks, it may be a piece of the puzzle.Julzes (talk) 01:36, 11 January 2010 (UTC)

Your reforestation assumption is far too imprecise to even begin to calculate a timeframe. Ariel is right, though, if you have a massive solar array then you don't need to worry about removing CO2 from the atmosphere. The current levels aren't problematic, it's the future levels if we continue to emit as we are that will cause problems. If you have the means to build massive solar arrays then we can pretty much stop all emissions and there won't be any problem. --Tango (talk) 01:16, 11 January 2010 (UTC)

Thanks. I and plenty of other people disagree with your claims. Current levels are responsible for past changes already. See graph and the introduction at global warming. Make my preferred specific date of 1932, and assume a long-term leveling of what needs to be combatted at 2020 current projections (continued rise in emissions to a leveling). Assume for forestation that as many trees as were on Earth and have been lost since 1932 (suicides of Hitler's niece and Stalin's wife) are replaced and allowed to start growing in 2020, just as an average planting date, for both CO₂-level dates. Assume algae and the rest of the flora are also functioning at the same date's level (in addition, since small trees won't fit that).Julzes (talk) 01:32, 11 January 2010 (UTC)

There have been changes, yes, but no large scale problems (there has, perhaps, been an increase in the rate of natural disasters like hurricanes and major flooding, but I haven't seen any convincing evidence that the increase is statistically significant, if it even exists). --Tango (talk) 01:41, 11 January 2010 (UTC)

Actual warming lags behind CO₂ (and CH₄, which may all dump into the atmosphere from more than one source over a short time-period), and you haven't read through it all if that's what you think. I really must disagree.Julzes (talk) 01:51, 11 January 2010 (UTC)

Rule out the need for any energy to be used at all for separation of CO₂ and do or do not consider the idea of conversion to a precipitate as an alternative to sequestration, as you prefer. There is no energy required for separation, as whatever excess heat there is in the processes may be directed to a ground site (at the equator) for reaching 40-degrees Celsius (as per the reference given on artificial trees above).Julzes (talk) 02:03, 11 January 2010 (UTC)

How can you rule that out? There are no methods of turning CO2 into a precipitate without input of energy. The 40-degree method uses change in humidity as the energy source. It might work for a small (tiny actually) "tree", but not for something like what you want. You are ruling out so many things you might as well get a magic wand. You need an energy source to remove CO2. If you have an energy source, forget about using it to remove CO2, and just use it directly instead of adding more CO2 in the first place. You've been told this before, but it seems to be a blind spot for you. Ariel. (talk) 02:47, 11 January 2010 (UTC)

I think I've met you halfway on this, and you have been sounding consistently intellectually rude (and ill-informed on the subject of global warming) since my last post. At any rate, how do you yourself know that change in humidity cannot be used for this rather than a small tree? I'll grant it's true, if you will explain this, as I am genuinely interested in preventing the catastrophe that I know is imminent (in generational terms, neither hstorical nor next-year terms).Julzes (talk) 03:11, 11 January 2010 (UTC)

I'm all for the cleanest nuclear fission as well as all the others at the same time, by the way, but I am quite convinced we will need to and will be scrubbing the atmosphere as well. I've actually put a bit of thought (if not actual hard-headed research) into the question, and you haven't said a single thing that might enlighten me until this comment about humidity and scale.Julzes (talk) 03:22, 11 January 2010 (UTC)

Oh, I do appreciate your calculation, FWIW. I'll check up on the whole calculation as it proceeds here.Julzes (talk) 03:25, 11 January 2010 (UTC)

Never mind trying to explain that changes of humidity can't be used for something this scale. That's false or I'll eat my shorts.Julzes (talk) 03:34, 11 January 2010 (UTC)

Everybody keep in mind that using energy at the location at which it is generated is much much more efficient than building infrastructure for transmission and for transmission itself. That said, once this devoted device had fulfilled its initial purpose, it could be used for Latin American energy needs.Julzes (talk) 03:38, 11 January 2010 (UTC)

One thing I'm a little interested in that I don't know about as well is whether space-to-ground transmission would best be accomplished by something changing the spectrum of the Sun's light--microwave or something.Julzes (talk) 04:17, 11 January 2010 (UTC)

I'm also aware of research that shows that CO₂ passed over a certain heated catalyst be used to make gasoline. If, as I assume, transformation to a precipitable chemical is innately endoergic, I will have fully conceded that sequestration and/or passing the gas over flora or a more efficient converter (in the future) in an intelligently designed system should be given the higher attention.Julzes (talk) 04:17, 11 January 2010 (UTC)

If you're right then I can make a perpetual motion machine by turning gasoline into CO2 by burning it and extracting the energy - and then converting the CO2 back into gasoline using some of that energy. Since perpetual motion is most definitely impossible (several of the laws of thermodynamics are very clear on this point!) it follows that any device that could convert CO2 into gasoline would require considerably more energy to do so than you'd get by burning the gasoline in the first place. That's really the problem with getting rid of CO2 by means other than sequestration (which is highly dubious for a bazillion other reasons). CO2 is in a very low energy state - which is what you'd expect from stuff that is the byproduct of energy extraction. Converting it to something different puts it into a higher energy state - and that's going to cost you power...probably LOTS of power. Pretty much anything you could do to remove the CO2 we added into the atmosphere would require more energy than the total amount that humans have gotten by burning things since the dawn of time. I suppose if we found a really cheap source of abundant non-CO2-forming energy somewhere - then we could use some of it to power our civilisation - and the rest to reverse the CO2 damage. However, if we had any hope of getting such a thing in the immediate future, we wouldn't be in the mess we're currently in because we could use it to simply remove the need to make more CO2 right now - which would be enough to save the planet if we could do it SOON. It's no good hoping for fusion of helium-3 obtained from the moon because by the time we get it the polar bears will be extinct and removing the CO2 won't bring them back. SteveBaker (talk) 05:02, 11 January 2010 (UTC)

What part of what I said didn't you understand? Maybe the word 'heated', perhaps. At any rate, when I said 'familiar' I should have hedged a little bit and the purpose of the process was not to generate energy out of nothing. Last I saw, there were not 'several' laws of thermodynamics, and I could continue with this. You obviously didn't understand the word 'endoergic' (or at least the sentence containing it). You needn't have replied so strenuously, your statement about Carbon Dioxide seems quite the logic I would use, and we're both basically on the same page about how bad things are.Julzes (talk) 06:34, 11 January 2010 (UTC)

Hold on now, I'm not convinced about the logic on burning. The same logic says that obviously such an apparently weak process as photosynthesis shouldn't be able to make anything for life out of the Carbon. I imagine that CO₂ is near minimum energy for the constituent elements, but to consider it rock bottom even with access to other elements doesn't sound right, at least to me. It's really almost the only thing fueling life itself (not human needs) on this planet.Julzes (talk) 06:45, 11 January 2010 (UTC)

What we need to do is reproduce the Azolla event which removed much of the earth's carbon dioxide using azolla. Graeme Bartlett (talk) 07:33, 11 January 2010 (UTC)

I'll buy that if things go really badly.Julzes (talk) 08:03, 11 January 2010 (UTC)

The energetics of CO₂<--->C(graphite)+O₂ are such that the compound on the left is more apt to turn into the mixture on the right than the reverse, right?Julzes (talk) 08:09, 11 January 2010 (UTC)That's what it looks like to me if it takes something like chromic acid to oxidize graphite (allotropes of carbon).Julzes (talk) 08:29, 11 January 2010 (UTC)

You mean the reverse of what you said. The one on the right will turn into the one on the left. And not "more apt". Will ONLY, this is not a statistical process, this in a one way processes. And CO2 is pretty much rock bottom - even with access to other things (except maybe fluorine compounds), CO2 is not what fuels life - sunlight fuels life.

"The same logic says that obviously such an apparently weak process as photosynthesis shouldn't be able to make anything for life out of the Carbon." ???? Are you serious? What kind of logic is that? Is it a question? If so, then no, that's not correct.

I hate to break Ariel's post in two here, but this was a response to someone else's ridiculous response to me on something else. The same logic as that person's logic.Julzes (talk) 10:27, 11 January 2010 (UTC)

You can't turn CO2 into ANYTHING else without input of energy (endoergic to use your words). Exactly the same energy as was released in making it in the first place. Trying to remove CO2 directly from the air is 100% pointless. Except that you can store the CO2 as is if you want. But that's about it. Anything else you want to do needs a source of energy. If you had such a source just use it to power everything else, and plants will handle the CO2. (The change is humidity energy source is tiny, very tiny. You need to cover practically the entire earth to harvest enough energy from it. And if you did that, I'd rather build a windmill, or a solar concentrator.)

And the saddest thing is we HAVE those energy sources. We just don't use them.

BTW, I'm sorry if I sound rude. I edited this many times, but I could not find any other way of getting the point across. Ariel. (talk) 08:45, 11 January 2010 (UTC)

I'm sorry, but I just don't see any hydrogen here. What you seem to say is heating oxygen gas and graphite with nothing else present will produce Carbon Dioxide. I suggest you try lighting some graphite (or diamond since it is less stable) on fire. The word is 'endoergic' (or endothermic if you prefer). Leave this question permanently, please. You seem like you don't know what you are talking about. I won't ask you again.Julzes (talk) 09:06, 11 January 2010 (UTC)

That's right, 'endogenic' was the wrong word.Julzes (talk) 09:27, 11 January 2010 (UTC)

It looks like Ariel might be (a little) right here. The enthalpy of formation of CO₂ is the same sign as that of water, which definitely means that graphite will burn; so I've asked a question about that below. (I have to say s/he has hardly been helpful and doesn't understand the situation all that well, FWIW.)Julzes (talk) 10:00, 11 January 2010 (UTC)

Ariel is right, graphite + oxygen is exothermic and will burn to CO2 while emitting about 390 kJ/mol (a relatively low number compared to most fuels but definitely exothermic). The reaction has a large activation energy, and so it is not easy to get it started. You need to heat it to about 300 C to kick off a reaction, and because graphite is highly thermally conductive, you need to heat a large volume at once, otherwise the heat will be conducted away rather than sustaining a reaction. Hence matches tend to be ineffective at lighting graphite because the area affected is too small. As Ariel says, CO2 is a low energy state, and most reactions to change it into other compounds require energy input. Dragons flight (talk) 10:11, 11 January 2010 (UTC)

Thanks. Well, I can fully erase the question below, since your post is just about as close as one could get to a direct answer to that one.Julzes (talk) 10:19, 11 January 2010 (UTC)

One logical possibility is that the optimal solution involves the conversion of some of the air into fertilizer. At any rate, whatever the full solution is is not likely to be found here.Julzes (talk) 12:25, 11 January 2010 (UTC)

This is where the editing is split by a hidden part.Julzes (talk) 02:21, 12 January 2010 (UTC)

The question was reposed at the top. If anyone wants to answer or see what answer is given, that is the place to go. Leave the earlier part alone or fold it up on my request if you know how to do it properly.Julzes (talk) 01:42, 12 January 2010 (UTC)

I'm fine with closing up that long part that got off topic, as I asked it to be partially closed rather than fully (in the hidden part).Julzes (talk) 02:38, 12 January 2010 (UTC)

This end is unacceptable to me--a number of related questions were asked, differing from the original. Please calculate the time for CO₂ in the atmosphere to reach mid-1932 levels assuming 1) That trees and other flora are restored to the numbers of that date with an average new tree planted in 2020 (spread them uniformly over 2010-30); 2) Emissions of the gas double in their decline relative to what their increase was around 2020 projections; 3) a device can remove all of the gas from a part of the atmosphere equivalent to passing air at altitude 1/2 mile through an aperture of diameter 1 mile at velocity 80 miles per hour, and one of these devices is placed in operation every five years from 2020 onwards. We won't talk about what would be done with the gas immediately after capture, if it's all the same to the people here (Just assume the energy source is strong enough to get a precipitable compound from CO2 and other gases and the substance is spread through global circulation and falls to the ground in an inoccuous way). That should be a precise enough question to be answered.Julzes (talk) 01:30, 12 January 2010 (UTC)

Respond, if one can, below the three part exchange that follows.Julzes (talk) 09:49, 12 January 2010 (UTC)

I don't care if you find it acceptable or not. Your attitude towards volunteers that have been trying to help you has been unacceptable to me and I am not going to allow it to continue. If you wish to object to this decision, please do so at Wikipedia_talk:Reference desk. --Tango (talk) 02:02, 12 January 2010 (UTC)

Going off topic to avoid dealing with the likely need for geoengineering as well as all the other stuff that's slow to change is what I saw being done by the person in question (and others, like yourself). That said, I'll accept the calculation at about 1500 years for all the way back to the start of the industrial revolution with a single device with altitude treated as at sea-level and diameter 1km and speed 100km/hr as well done.Julzes (talk) 02:49, 12 January 2010 (UTC)

Now, no more posts about people here, please. This is not about me, Tango, or the one person I laid into a little bit (who laid into me first by expressing that my question was pointless and other somewhat irrelevant things).Julzes (talk) 02:16, 12 January 2010 (UTC)Anybody who wants to take a shot at the complications here, after this is the proper place. The part on emissions means that whatever the increase is expected to be in 2019, double that is the decline in 2021.Julzes (talk) 02:28, 12 January 2010 (UTC)

At WMC's talk space, I've thrown in another condition for calculation for comparison purposes that might get around the same teperature. It's more complicated still, but perhaps it can be done. Still get the time period under identical conditions but for 1979 as the date in place of 1932 and with cool roof (reflective) technology being uniformly brought to universality in 2030. So, two sets of conditions wanting the time period required and also whether this later set of conditions is as cool as 1932 conditions would be. The second set should be much faster and it also requires a less dubious condition on flora restoration.Julzes (talk) 17:36, 12 January 2010 (UTC)

I can understand this question not getting much attention at this point. What I cannot understand is why nobody knew or bothered to state that both Magnesium Carbonate and Calcium Carbonate creation releases energy from Carbon Dioxide. Hmph!! Julzes (talk) 14:27, 13 January 2010 (UTC)

...because it does not, or at least not with commonly available input material. It you have raw, elementary calcium or magnesium, then yes - but again, in that case you can just burn the metals for energy. But neither unoxidized calcium nor unoxidized magnesium are available in significant amounts in nature. --Stephan Schulz (talk) 14:47, 13 January 2010 (UTC)

Well a little elucidation of the whole question could have been a good thing. Anyway, the claim that CO₂ is pretty much rock bottom for Carbon was wrong. Now, combining anything naturally occurring with CO₂ to get a release of energy may be impossible on a large enough scale, but to treat that as obvious is a bit superficial.Julzes (talk) 17:21, 13 January 2010 (UTC)

"Well a little elucidation of the whole question could have been a good thing." Which was what Ariel, among others, tried to do. Look at how you reacted to that. Nobody else wants to be spat on for trying to help. 86.178.229.168 (talk) 16:27, 14 January 2010 (UTC)

You seem to me to be misinterpreting what Ariel was doing.Julzes (talk) 17:05, 14 January 2010 (UTC)

Human hair: stripes and dots?

I'm wondering if there has ever been a case of a human with hair (obviously head hair would be the best candidate here) that showed signs of being striped, dotted, or somehow patterned in the way other mammals (zebra, cheetah, panda) are, presumably due to the mutation of a certain gene/genes. If not in humans, perhaps in an animal that, like humans, is known for having single-tone fur (polar bear, squirrel?, lion?). I am of course referring to naturally occurring phenomenon, not like lion-zebra hybrids : D. 219.102.221.49 (talk) 02:18, 11 January 2010 (UTC)

Well, there are no spotted wolves - but there are plenty of spotted dogs - and dogs are descended from wolves. SteveBaker (talk) 02:42, 11 January 2010 (UTC)

Lion-zebra hybrids?!? Talk about "playing with your food"! APL (talk) 02:59, 11 January 2010 (UTC)

I think that a Chimera (genetics) might have two-toned fur or hair where you would expect a single-tone coat. APL (talk) 03:04, 11 January 2010 (UTC)

Cows and horses are also descended from animals of single tone fur. Many cows and horses are still of single tone, but many have also been bred for multi colour spots and patterns. The patterns were not "put" there by humans, the patterns were a naturally occurring phenomenon which has for thousands of years and probably hundreds of generations been selected for by humans. The thing you have to keep in mind is that no one would even claim that spots or stripes all of a sudden APPEARED in zebras or tigers after one generation, like your question implies you think it might. Those characteristics mostly evolve by very small increments, typically imperceptible from one generation to the next. There is absolutely NO reason to think spots must be present in the human population for spotty animals to have evolved, just as there is no reason to think some humans must have trunks for elephants to have evolved. Vespine (talk) 03:14, 11 January 2010 (UTC)

Darwin (in OoS) seemed to think that horses were partly or wholly evolved from a striped species, due to the occasional appearance of stripes in related hybrids and "monstrosities", but I don't know about cows. I'd like to think though, that the increments would be noticeable, though maybe only to a breeder with a good eye. On that point, I suppose it wouldn't be strange then if there were common mutations in the human genome producing striped/patterned hair that was merely too faint to be significant. 219.102.221.49 (talk) 03:47, 11 January 2010 (UTC)

Human hair is too long to be "spotty." Humans do occasionally display gradations of color throughout the head. It is not generally particularly pronounced. More commonly there are gradations of hair color on different parts of the scalp. The nape of the neck is sometimes different than the top of the head; similarly around the temples. But long hair might tend to disguise this. Bus stop (talk) 03:21, 11 January 2010 (UTC)

You may want to read Cat coat genetics for the mechanisms defining the (multi)color patterns of cat fur. It does not work the same way in humans, though. --Dr Dima (talk) 03:23, 11 January 2010 (UTC)

Thanks for the responses! 219.102.221.49 (talk) 03:47, 11 January 2010 (UTC)

I rather agree that the length of the hair makes a clear identification difficult. I have a very full beard - and as I age, parts are going grey - my chin is grey and I'm grey next to my ears but my cheeks are still brown. Technically, I have several grey "spots" (or maybe "stripes")...but nobody seems to think of it like that though. SteveBaker (talk) 04:37, 11 January 2010 (UTC)

That's odd -- I always thought of you as a 30ish whippersnapper. DRosenbach ^{(Talk | Contribs)} 18:29, 11 January 2010 (UTC)

"I am not getting old! I am simply turning into a gray dalmatian!" 219.102.221.49 (talk) 05:47, 11 January 2010 (UTC)

FRED: Your face is lined, your hair is grey

RUTH: It’s gradually got so.

-- W. S. Gilbert Cuddlyable3 (talk) 12:57, 11 January 2010 (UTC)

For what it's worth, Waardenburg syndrome is remarkable for a "white forelock" of hair, which helps to make it one of the more easily recognized genetic syndromes. Other terms used to describe this phenomenon are poliosis and piebaldism, which refer to depigmented patches of hair. In some cases, piebaldism is genetic, although it seems as though the genes affect hair pigment itself, not so much the patterning of pigmentation. --- Medical geneticist (talk) 19:09, 11 January 2010 (UTC)

I have heard the term "witch lock" or "witch's lock" for a natural streak of white or blond hair in an otherwise dark head of hair. But Google returns few uses of those terms. 75.41.110.200 (talk) 15:51, 12 January 2010 (UTC)

Mirrors and their color

I've been spending a lot of time thinking about mirrors lately (the normal, flat, glass-fronted, silver-backed kind), and I find the idea of a mirror's color to be very strange: While the mirror is reflecting a 100% accurate picture of me, I still know, without being told, that the mirror is also silver colored at the same time.

How is this possible? How is the mirror reflecting a complete image of me and my surroundings (and their completely non-silver colors) and I still have this niggling (almost subconscious) knowledge that the mirror is silver at the same time? ~fl 03:43, 11 January 2010 (UTC)

Could it be the other way around? I imagine silver is really just a grayish mirror, and though a true mirror has no color at all, your mind might register it as "close to silver", assigning by association the color "gray". Just wondering out loud : ) 219.102.221.49 (talk) 03:52, 11 January 2010 (UTC)

Keep in mind that no mirror truly reflects 100% of the light that hits it; reading our article, I see that even a high grade technical mirror only reflect abour 90-95% of the light, when new. I imagine that different wavelengths are absorbed in different amounts, which may give rise to a "silverish" mirror (pure spectulation on my part). There's probably also some psychological element too, given that you know that a mirror is glass that has been "silvered" (again, I'm just speculating). Buddy431 (talk) 04:11, 11 January 2010 (UTC)

(So does a white object...that's not a good answer!) SteveBaker (talk) 04:21, 11 January 2010 (UTC)

The problem is what we mean by "The color of an object". It's a typically human, imprecise, piece of terminology...one that gives computer graphics guys like me endless headaches when dealing with artists and designers.

Silver isn't really a color. Look at a spectrum - there is no frequency or combination of frequencies in the light that is "silver". You can't mix "silver" in Photoshop using just red, green and blue - yet those are all our eyes can see. The closest we can get is "grey". So where is "silver"? If you look at a photo of a "silver" car on your computer monitor - it's only made up of the same reds, greens and blues - so how come you can get silver in a computer photo - but not mix it yourself? What happens if you bring the photo into photoshop and grab a bit of the car with the eyedropper tool? You get grey.

The problem here is that our concept of "color" is a bit flakey.

When light hits a surface, three entirely different things happen:

1. Some percentage of the light (more or less regardless of frequency) is simply bounced off in a direction that's fairly close to the angle at which it came in (this is "specular reflection").
2. Some percentage of the light is absorbed by the surface (in some specific range of frequencies that depend on the chemistry of the material).
3. What's left is scattered off more or less uniformly in all directions (this is "lambertian reflection")

Those three things have to add up to 100% of the incoming light because all of the light has to go somewhere (well, except for objects that glow in their own light, translucent objects, etc - but let's ignore those for the sake of a simple explanation).

The thing we consider to be the "color" of the object is only the lambertian reflection part - the light that's scattered uniformly without being absorbed. We say that because that is the only set of frequencies that seems to be innate to the nature of the object - but that's not very scientific - which is why the concept breaks down for things like mirrors. In white light, a red plastic ball has a really bright white 'shiney spot' on it - but somehow that doesn't matter, we don't say that this is a "white" ball. We say that the ball is "red" - even though there is a ton of white light being specularly reflected in a certain small set of directions.

In the case of a mirror, close to 100% of the light is specularly reflected (90% or more) - leaving almost zero percent being either absorbed or lambertian-reflected. So if you had to use the same naming rule you used for the shiney red ball - you'd have to say that the mirror was "black"...which is the closest you're going to get to a good answer to your question! An object that has only 5 to 10% of lambertian reflection is either black or a very dark grey.

For some reason, we have no problem labelling a car with really shiney black paint as "black" - because in that case, even though there is not much lambertian reflection, a lot of the light shining onto the car is being absorbed - so far less than 100% is being specularly reflected. A black car doesn't look like a "silver" car.

The difference between "silver" (like the color of the unpolished metal) and "mirror" is the precision with which the specular light is reflected at PRECISELY the same angle as the light came in at. Mirrors (and highly polished metals like silver) do that reflection so precisely that a nice sharp image is formed. Unpolished silver reflects a similar amount of specular light to a smooth mirror - but it's not reflected at precisely the incoming angle - so a proper, sharp image doesn't form...although a softly blurry one might. What we're talking about now is not the "color" at all - but the "shininess", which is really a different concept. However, we know that the petal of a red flower, a red plastic ball and a shiney red car can all be the same "color" - even though the nature of the specular reflection is wildly different between the three of them.

SteveBaker (talk) 04:21, 11 January 2010 (UTC)

Paraphrasing Steve's coment above (But with much reduced wordyness): Silver ain't a color. Dauto (talk) 05:13, 11 January 2010 (UTC)

So who's going to delete the Wikipedia article, and update Wiktionary? We'd better let Oxford Press know that their dictionary is wrong as well. Mitch Ames (talk) 09:30, 11 January 2010 (UTC)

And then there's the Crayola corporation....

Just the same, in context, the claim is true; that sort of silver, at least, is not a color. --Trovatore (talk) 09:34, 11 January 2010 (UTC)

The OP did explicitly say "... a mirror's color ..." and "... the mirror is also silver colored ...". Mitch Ames (talk) 10:18, 11 January 2010 (UTC)

Right. That's precisely the sort of silver that isn't a color. There is a color called silver; it's sort of a light gray. But it has nothing to do with mirrors. --Trovatore (talk) 10:33, 11 January 2010 (UTC)

... and some "silver colours" combine the light grey with tiny reflective patches from which light is specularly reflected (like a mirror) to give a "shiny" or "metallic" silver. We tend to use the name "silver" for a range of reflective surfaces from a "proof" silver coin that is almost like a mirror, through matt silver that has some specular reflection, to just a shade of light grey with purely lambertian reflection. Dbfirs 10:45, 11 January 2010 (UTC)

See [2] and scroll down to the bottom two images. The bottom shows specular + Lambertian, the one above shows specular only (mirror) reflection. Cuddlyable3 (talk) 12:43, 11 January 2010 (UTC)

I'm not saying that people should stop saying that mirrors are silver or that they should stop thinking of silver as a "color". I'm merely trying to point out that the english language is imprecise (well, there's a shock!) and that in order to answer the question of what color a mirror really is, we have to understand why this is a question of linguistics and not a question of science. If you want a scientific answer then it is undoubtedly that silver isn't a "color" and that mirrors are really shiney black objects. If you only want a linguistic answer then (a) don't ask the science desk and (b) you already know that you want to call it "silver" so why bother asking?

So let me see if I understand Steve's answer correctly. Most of the light that hits a mirror (say 90%) is reflected at a similar angle that it came in at (called specular reflection). This is what makes a mirror usefull as a mirror. Of the remaining 10%, some (most?) is scattered in all directions (called lambertian reflectance), and this is what gives any object its "color" in a strict sense. The rest of the light is absorbed. In a mirror, the "color" caused by the lambertian reflection is a gray. When our minds see both this gray color, and a large amount of specular reflection, we say that a material is "silver".

I suppose that the same could be said for other metalic colors as well. When I say that a polished gold coin is "gold", what I really mean is that the lambertian reflection gives the coin a yellow or orange color, but the coin also reflects a large amount of light hitting it out at a similar angle to what came in. Buddy431 (talk) 15:37, 11 January 2010 (UTC)

Yes - I think you have that right. I don't honestly know how much of the light hitting a mirror that is not specularly reflected ends up being absorbed and how much becomes lambertian reflection. My guess is that for reasonably good mirrors and surfaces like chrome, almost everything that remains (after specular reflection has taken it's share of the incoming light) is absorbed...but for less good mirrors, perhaps there is still some lambertian reflection going on - I kinda doubt it. Hence, IMHO, mirrors are "black". SteveBaker (talk) 18:45, 11 January 2010 (UTC)

I would say that for a mirror, "silver" and "gold" come from the metallic elements. An ordinary mirror is silver in the sense that its reflectivity spectrum is roughly flat over visible wavelengths—silver, the element, has this property, but so does aluminum. Gold, on the other hand, reflects blue light poorly, giving a gold-coated mirror (as used on infrared telescopes, for example) its distinctive appearance. Reflectivity has a nice plot of reflectivity spectra. -- Coneslayer (talk) 14:35, 12 January 2010 (UTC)

Bathroom Bacteria Aerosol

Which lowers the spread of bacteria from a toilet flush? Putting the lid down or leaving it up? Does leaving it up directly expose its surroundings or does leaving it down incubate the aerosol after a flush?--99.11.199.76 (talk) 03:49, 11 January 2010 (UTC)

I can't answer your question - so I'm going to tell you why it's irrelevant instead! Countless studies (my favorite being two different tests from the Mythbusters) show that toilet seats are one of the cleanest places in the house. The hard, non-porous surfaces have zero nutrients - very little moisture and may be sprayed with urine (which is an antibacterial agent) and are frequently exposed to light - that's a very hostile place for bacteria to live. So don't worry about it. You should be much more concerned with (IIRC) the various sponges and pads used around your kitchen, your light switches and your computer keyboard. All of those are full of NASTY bacteria. You could quite safely eat lunch off of your toilet seat...but you should seriously consider washing your hands after using the computer and keeping food away from the keyboard area altogether. SteveBaker (talk) 04:02, 11 January 2010 (UTC)

Whilst I agree with SteveBaker (above), it must surely be true that putting the cover down before flushing must reduce the aerosol that travels to nearby porous, nutrient-rich surfaces. Has any research been done on this? The human body is adapted to cope with almost all normal bacteria, it is only the unexpected (and virulent) ones that cause illness, and they can be spread in so many other ways. Do most users never clean their computer keyboards? Dbfirs 08:17, 11 January 2010 (UTC)

In ~20 years of using computers I've never once cleaned a keyboard... ok, I did it ONCE, but that was only because I spilled 2 liters of coke across it and all the keys stuck... 218.25.32.210 (talk) 08:34, 11 January 2010 (UTC)

I agree - but humans are much less vulnerable to bacterial diseases than most of us think. It's widely believed that being overly clean is the reason that allergies and asthma are on the increase - and using antibacterial agents is guaranteed to cause them to become less effective over time as the bacteria evolve resistance. If we don't get regular exposure to the 'stuff' in our environment, our immune systems don't develop the necessary resistance to them. So NOT obsessively cleaning things that are not a realistic and serious threat is probably counter-productive in the longer term. Also, most keyboards are used predominantly by just one person at work - or by a few family members in the home - that means that whatever nastiness there is there was probably put there by you - so you're already exposed to whatever nastiness is there. Hence I would certainly consider cleaning a keyboard that a large number of strangers use - but not the ones I use at work and at home. Similar arguments apply to light switches. SteveBaker (talk) 14:46, 11 January 2010 (UTC)

Yes, I remember many years ago a large amount of coke being spilled into an Archimedes school computer where the keyboard is built-in. I took the machine apart and washed the keyboard under the hot tap, and it worked perfectly (better than the others) thereafter. Dbfirs 10:35, 11 January 2010 (UTC)

I wash mine, but not antibacterially. Mythbusters has also shown that the aerosol effects of flushing toilets are virtually nonexistent - a few dozen toothbrushes used for brushing teeth were virtually indistinguishable with regards to bacteria count, no matter where they were kept - near the toilet, other side of the room, even in a diferent room. Vimescarrot (talk) 10:55, 11 January 2010 (UTC)

If you watched their 'extra' material on their website, it turned out that the bacteria that was on the brushes came from the people using them - not from the bathroom environment they were kept in. SteveBaker (talk) 14:46, 11 January 2010 (UTC)

So there really is very little risk from the "aerosol" effect on flushing a toilet, and we might as well leave the cover up (as I always do anyway)? Why, then, do health authorities make such a fuss about the risk of "coliform" bacteria? Is there a much higher risk from hands? Dbfirs 08:25, 12 January 2010 (UTC)

Coliform bacteria are easy to spot, so they're used as a proxy for other, hard-to-spot hazards. --Carnildo (talk) 01:30, 13 January 2010 (UTC)

1,3,5 trihydroxyhexane

Does this compound exist? Or does it too easily convert to benzene? (I hate it when you google volatile compounds like that and they don't tell you why it doesn't exist.) John Riemann Soong (talk) 04:20, 11 January 2010 (UTC)

Are you thinking of 1,3,5 trihydroxycyclohexane? This is more likely to form benzene by eliminating water. Graeme Bartlett (talk) 07:24, 11 January 2010 (UTC)

Yeah that important cyclo description. Yes. What I'm thinking of not the synthesis of benzene itself, but the synthesis of substituted aromatic rings via substituted 1,3,5 trihydroxyhexanes (with aldol condensations and the like and reductions in the right places). Induce aromaticity, and boom! No need to worry about nasty Acyl-Crafts reactions. John Riemann Soong (talk) 07:32, 11 January 2010 (UTC)

"1,3,5 trihydroxyhexanes "...dude--you just said cyclo is important and that you are having trouble finding info because you don't know what terms to use...start by using something even close to chemically correct for your situation even if not best!

What's the basis for thinking these compounds are very volatile? Polyhydroxylation raises bp substantially (why?). None of the isomers (structural nor stereo) of trihydroxy-n-hexane nor of trihydroxycyclohexane are particularly volatile--bp are well over 100°C (sometimes up to several hundred at <1mmHg!). DMacks (talk) 07:44, 11 January 2010 (UTC)

Volatile as in "reactive" (layman's term), that is, it quickly forms something else a la carbamic acid. It's nice to have them above the BP of water since you can distill water all you want and not worry about your product evaporating. :) John Riemann Soong (talk) 08:03, 11 January 2010 (UTC)

Mass Difference of Chemical Bonds

What is the the average mass of a Carbon atom in graphite plus the mass of an Oxygen molecule minus the mass of a Carbon Dioxide molecule to as high a precision as known at present? I know that there is mass in the motions of the electrons and I'd like to know if the one-and-a-half single bonds plus whatever the other half bond of the floating electron is called in Graphite is heavier or lighter than one of the double bonds in CO₂ and by how much. A scaled up answer is fine. I can handle the basic stuff.Julzes (talk) 09:44, 11 January 2010 (UTC)

Better Question

Resolved

What temperature is required to burn transform Oxygen gas plus Graphite into Carbon Dioxide, as I now see it can be done from standard enthalpy of formation (and burning is the wrong word)? What is the activation energy?Julzes (talk) 10:12, 11 January 2010 (UTC)

It's easier if you start with the enthalpy of formation at room temperature and then scale based on specific heat capacity accordingly. (btw, if the mass contribution by electronic bond stabilisation is small... the fluctuations to the overall mass because of heat capacity is even smaller...)

In fact I'm sure it's already been done for you, so you actually don't need to do any work. For example the enthalpy of formation of say, CO2 or CO at 25C already has been compensated for, prolly by taking a reaction that might start at 200C and scaling based on heat capacity. John Riemann Soong (talk) 10:13, 11 January 2010 (UTC)

What does enthalpy of formation have to do either with temperature or with activation energy (which have more to do with each other)? If you look up that enthalpy and the heat capacities, you'll be able to tell what temperature difference results from the reaction, but I would interpret the question (especially with its activation energy component) as referring to the autoignition temperature of graphite (although that probably depends weakly on the concentration of oxygen, so you'd need to specify if it's normal air or oxygen at one atmosphere or what). That temperature is surely related to the activation energy via the Arrhenius equation: it should be very approximately $E_{a}/k_{B}$. --Tardis (talk) 15:28, 11 January 2010 (UTC)

Well, when I marked it resolved, it was answered well enough for me. I was mainly concerned with the practical issue of Carbon capture and sequestration, and it's been resolved for me that if I want to make an enormous fan and chemical reaction of CO₂ plus other substances in the air to a precipitable compound and then back into the atmosphere, then the chemical process is going to require rather than release energy because CO₂ is pretty much rock bottom (which I would have guessed originally, before this graphite thing entered my mind). Okay?Julzes (talk) 16:25, 11 January 2010 (UTC)

This status of CO₂ is incorrect. Calcium and Magnesium can be reacted with Carbon Dioxide with the release of energy.Julzes (talk) 14:33, 13 January 2010 (UTC)

OK: glad you're happy with it. I hope my further information is at least of some interest. I put the tag back. --20:30, 11 January 2010 (UTC)

Btw, carbon has no lone pairs in graphite. Graphite has a polyaromatic structure. John Riemann Soong (talk) 10:18, 11 January 2010 (UTC)

Really? I didn't know that.;-)Julzes (talk) 12:48, 11 January 2010 (UTC)

Dragon'sFlight gave plenty of detail on this just when I was asking it in the other question I asked. Thanks anyway.Julzes (talk) 10:17, 11 January 2010 (UTC)

F. B. H. Brown

I'm having trouble finding biographical information about Yale botanist F. B. H. Brown, also known as Forest Brown, sometimes as Forest B. H. Brown. There seems to be someone of the same name who worked for the USDA or some other government organization, but I'm not sure if it is him or his father, or a relative or someone else entirely. If anyone can point me in the right direction, that would be great. Viriditas (talk) 10:07, 11 January 2010 (UTC)

Found this reference in Google Books [3]. The Bernice P. Bishop Museum may be able to help. Alansplodge (talk) 11:46, 11 January 2010 (UTC)

I doubt they can help. I'm actually looking for information prior to and subsequent to his work with the Bishop Museum. Something on the order of this from Yale. Are there are any Yale archives available on their site? Viriditas (talk) 13:18, 11 January 2010 (UTC)

The one who went on the Bayard Dominick Expeditions? --BozMo talk 13:34, 11 January 2010 (UTC)

Yes, that's him. Viriditas (talk) 13:37, 11 January 2010 (UTC)

few mentions around the place like "Forest B. H. Brown, Botanist, returned to Honolulu on December 16, 1922, after a period of two years spent in the Marquesas and neighboring parts of the Pacific as a member of the Bayard Dominick Expedition. His work has resulted in filling a conspicuous gap in the knowledge of Pacific flora and should lead to the preparation of a standard treatise based on his collections, which comprise 9000 sheets of material and 395 photographs. During the year a paper by Mr. Brown on "The secondary xylem of Hawaiian trees" (Occasional Papers. Vol. VIII, No. 6) was issued by the Museum." --BozMo talk 13:40, 11 January 2010 (UTC)

I get the general impression there is quite a lot of stuff but you are handicapped by the fact he is called "Mr Brown" everywhere. Multi word searches keep turning up snippets. Any particular type of thing? --BozMo talk 13:42, 11 January 2010 (UTC)

Well, I've got that already here, but I'm looking for biographical information, such as birth, career highlights, and death because I want to create an article about him. JSTOR has several reviews, but very little bio info. I'm still curious if he's the same Brown who worked for the USDA. Viriditas (talk) 13:48, 11 January 2010 (UTC)

Ok, other ideas "Forest Buffen Harkness Brown" as a google search also turns up some stuff. Forest Buffen Harkness b 11 Dec 1873, Rushville, NY. AB, Univ Mich, 1902; AM, Univ Mich, 1903. Am Men Sei ed 3,4,5. etc--BozMo talk 13:51, 11 January 2010 (UTC)

That's interesting. I'll go from there. Thanks. Viriditas (talk) 13:54, 11 January 2010 (UTC)

explain the name of acetoacetaldehyde

Like, I'm actually trying to find what I thought would be a relatively simple compound, that is, 1,3-dioxobutane. Unfortunately, 1,3-dioxobutane doesn't seem to be used that often (either as the name or the chemical), so now I try some aldehyde nomenclature.

"If replacing the aldehyde group with a carboxyl group (-COOH) would yield a carboxylic acid with a trivial name, the aldehyde may be named by replacing the suffix -ic acid or -oic acid in this trivial name by -aldehyde. For example:"

So ooh, I could use acetoacetic acid, and then back-form acetoacetaldehyde, right?? Well, apparently googling this gives a KETONE, not an aldehyde. Someone please explain the insanity of this nomenclature. John Riemann Soong (talk) 15:26, 11 January 2010 (UTC)

There do appear to be two different chemicals that have "acetoacetaldehyde" as their name according to google. One is what you want, but it's not the first hit for that name. Great example of why simple web-searching always requires human sanity-checking to filter out hits that use a term in a way you don't mean. One reason the compound you want isn't easily found is that it doesn't actually exist in that form (except maybe as a transient intermediate in a reaction flask). DMacks (talk) 16:34, 11 January 2010 (UTC)

Wait ... do I get a conjugated enol ... ? H-bond + conjugation stabilisation, I guess? Btw, what's the thermodynamic difference between an enol and a ketone form usually? Before last year I didn't know it was that small as to be overcome by H-bond and conjugation which IIRC only provide max 5-15 kcal/mol of stabilisation. John Riemann Soong (talk) 01:18, 12 January 2010 (UTC)

Proton NMR

In the proton NMR spectrum for RuClH(CO)(PPh₃)₃ there is doublet of triplets (two sets of three peaks, with the peaks in the ratio 1:2:1) at about -7ppm. It is clear that this is the hydride ligand on the ruthenium, but I do not know why it has split in such a way. I understand that phosphorus will split the peak, but I cannot see how it is possible to end up with a doublet of triplets. Similarly, how would the splitting pattern be if there were two hydrides instead of the a hydride and a chloride? 188.221.55.165 (talk) 16:22, 11 January 2010 (UTC)

There must be two equivalent phosphorus atoms and one unique phosphorus - makes sense if the complex has this structure, as determined by XRD in this paper and others before it.

Ben (talk) 18:52, 11 January 2010 (UTC)

Derailed on the uses of trona

Watching a show on the train 7551 derailment, I got to wondering about the trona it was carrying. The NTSB says it's "used in the manufacture of fertilizer".[4] Our article just says that trona is a source of soda ash (sodium carbonate). Our sodium carbonate article mentions use for making glass, melting flesh off skulls, use in both bricks and food (comforting that) but nothing about fertilizer. Except one mention of a modification of the Solvay process (which trona mineral bypasses anyway) where the "byproduct" ammonium chloride can be used as a fertilizer. Our ammonium chloride article mentions use in oil wells, food, explosives - but not in fertilizer.

So what am I missing? How is trona used to make fertilizer? And how is ammonium chloride used to make fertilizer? Franamax (talk) 16:27, 11 January 2010 (UTC)

Trona is used for the Solvay process purely to create the ammonium chloride, which is a good source of nitrogen for fertilizers. See the ammonium chloride entry in the Fertilizer Encyclopaedia. Nanonic (talk) 17:33, 11 January 2010 (UTC)

Protein Shakes

Is there any unbiased scientific evidence that ingesting protein shakes while practicing an exercising regimen increases the amount of muscle tissue built up? By unbiased I mean studies not performed or funded by companies/parties with interest in protein shake sales. Something tells me all they do is fortify one's poop. 71.161.49.93 (talk) 23:44, 11 January 2010 (UTC)

Probably not much effect if the basic diet contains adequate protein -- see this article for a review of the science. Looie496 (talk) 00:11, 12 January 2010 (UTC)

It is physiologically true that ingesting high protein beyond that of daily values during adolescence (for growth and development) and rigorous body building increases muscle mass. An adult that ingests a high protein diet without regimented and prolonged exercise will not increase muscle fiber size. Wisdom89 _{(T / ^C)} 00:34, 12 January 2010 (UTC)

... --Jayron32 00:41, 12 January 2010 (UTC)